A battery formation method, a battery manufacturing process, and a battery

Abstract

The application relates to a battery formation method, a battery preparation process and a battery, and relates to the technical field of battery preparation. The battery formation method comprises the following steps in sequence: first charging, charging the battery to a cut-off voltage V1 by using a current I1, and then standing for a standing time t1. Second charging, charging the battery to a cut-off voltage V2 by using a current I2, and then standing for a standing time t2. Third charging, charging the battery to a cut-off voltage V3 by using a current I3, and then standing for a standing time t3. Wherein, the cut-off voltage V1 is configured as 2.7V-2.9V, the cut-off voltage V2 is configured as 3.1V-3.3V, the cut-off voltage V3 is configured as 3.2V-3.4V, and the standing time t1, the standing time t2 and the standing time t3 satisfy t1>t3 and t2>t3. The battery formation method provided by the application improves the film forming quality of the SEI film by improving the battery formation method, and then improves the cycle service life and other performances of the battery.

Description

Technical Field

[0001] This application relates to the field of battery manufacturing technology, specifically to a battery formation method, a battery manufacturing process, and a battery. Background Technology

[0002] With the rapid development of new energy technologies, the application of new energy batteries, represented by lithium-ion batteries, is becoming more and more widespread, which in turn leads to higher requirements for the performance of new energy batteries.

[0003] In the process of new energy battery manufacturing, formation is a crucial step. By charging with a small current, the electrolyte components form a solid electrolyte interphase (SEI) film on the surface of the battery active material. The quality of the SEI film formation directly affects the final performance of the battery.

[0004] Therefore, there is an urgent need to provide a battery formation method that improves the formation quality of the SEI film, thereby enhancing the battery's cycle life and other performance characteristics. Summary of the Invention

[0005] The purpose of this application is to provide a battery formation method, a battery manufacturing process, and a battery. By improving the battery formation method, the film quality of the SEI film is improved, thereby enhancing the cycle life and other performance characteristics of the battery.

[0006] To achieve the above objectives, in a first aspect, this application provides a battery formation method, which includes the following steps in sequence: For the first charge, the battery is charged with current I1 to the cutoff voltage V1, followed by a resting time t1.

[0007] The second charge involves charging the battery with current I2 to the cutoff voltage V2, followed by a resting period of t2.

[0008] The third charge involves charging the battery with a current I3 to the cutoff voltage V3, followed by a resting period of t3.

[0009] Among them, the cutoff voltage V1 is configured to be 2.7V~2.9V, the cutoff voltage V2 is configured to be 3.1V~3.3V, the cutoff voltage V3 is configured to be 3.2V~3.4V, and the settling time t1, settling time t2, and settling time t3 satisfy t1>t3 and t2>t3.

[0010] Based on the embodiments described above, during battery formation, the negative electrode active material expands during charging, causing damage to the solid electrolyte interphase (SEI) film formed on the surface of the negative electrode active material. Correspondingly, the faster the SEI film formation rate during charging, the more pronounced the expansion of the negative electrode active material becomes, leading to more severe damage to the SEI film already formed on the surface of the negative electrode active material.

[0011] In this application, the battery formation process is divided into three charging cycles and a resting cycle, with specific limits set for the cutoff voltage and resting time during each of the three charging cycles. Specifically, the cutoff voltages for the three charging cycles are 2.8V±0.1V, 3.2V±0.1V, and 3.3V±0.1V, respectively. Experimental results show that the voltage increase rate slows down around 2.8V and 3.2V, indicating a faster film formation rate at these two potentials. Similarly, the film formation rate is relatively fast at 3.3V. Based on this, the cutoff voltages for the three charging cycles are set to approximately 2.8V, 3.2V, and 3.3V, enabling the surface of the negative electrode active material to form a large-area solid electrolyte interface film at a high film formation rate during the three charging cycles.

[0012] Meanwhile, a resting time is set after each charge-to-film formation. During this time, metal ions in the negative electrode active material undergo deintercalation and reaction with the electrolyte to form a film, thereby repairing the solid electrolyte interface film damaged by the expansion of the negative electrode active material. During the first and second charges, the solid electrolyte interface film formation rate is high, resulting in significant expansion of the negative electrode active material and more noticeable damage to the formed solid electrolyte interface film. Therefore, a longer resting time is set in these cases to allow sufficient time for the battery to repair the solid electrolyte interface film. During the third charge, the film formation rate is lower than in the first and second charges, and the expansion of the negative electrode active material is relatively less. A shorter resting time can be set in this case, thus achieving both solid electrolyte interface film repair and formation efficiency.

[0013] In summary, this application divides the charging process during battery formation into three steps, and limits the cutoff voltage for each of the three steps, thereby improving the film formation rate of the solid electrolyte interfacial film during formation. Furthermore, a resting time is set after each charge, with a longer resting time for charging processes with higher film formation rates, to repair the solid electrolyte interfacial film damaged by the expansion of the negative electrode active material. Finally, these settings improve the film quality of the solid electrolyte interfacial film, thereby enhancing the battery's cycle life and other performance characteristics.

[0014] In some embodiments, the current I1 is configured to be 0.08C~0.15C, and the settling time t1 is configured to be 10min~30min.

[0015] Based on the embodiments described above, specific limits are made to the initial charging current rate and the resting time. By setting a lower charging current rate, the proportion of inorganic matter in the formed solid electrolyte interface film increases, thereby improving the ionic conductivity and other properties of the solid electrolyte interface film, and enhancing the film formation quality. The specific limitation on the resting time ensures sufficient time for the battery to repair the damaged solid electrolyte interface film while also maintaining formation efficiency.

[0016] In some embodiments, the current I2 is configured to be 0.1C to 0.2C, and the settling time t2 is configured to be 10min to 45min.

[0017] Based on the embodiments described above, similar to the initial charge, the current rate and resting time for the second charge are specifically defined. At this time, the charging current rate is increased compared to the initial charge, while still remaining at a relatively low current rate, thus ensuring both charging efficiency and film formation quality. The resting time is similar to that of the initial charge, taking into account both the repair of the solid electrolyte interface film and formation efficiency.

[0018] In some embodiments, the current I3 is configured to be 0.15C to 0.3C, and the settling time t3 is configured to be 1min to 5min.

[0019] Based on the embodiments described above, the current rate and resting time during the third charge are also limited. At this time, the charging current rate is further increased compared to the first and second charges, allowing for a faster completion of the final charging process at a higher charging rate, thus improving formation efficiency. Simultaneously, the solid electrolyte interface film shows less damage during the third charge, therefore a shorter resting time is set to further improve formation efficiency.

[0020] In some embodiments, the battery formation method further includes: high-temperature aging, which involves heating a fully charged battery to a temperature T and storing it for a time t4 to optimize the film formation effect.

[0021] Based on the above embodiments of this application, after charging and formation, the fully charged battery is heated at high temperature to activate and decompose some residual components in the solid electrolyte interface film, thereby further improving the film formation effect of the solid electrolyte interface film.

[0022] In some embodiments, the temperature T is configured to be 45°C and the time t4 is configured to be 12h-48h.

[0023] Based on the embodiments described above, by specifically limiting the heating temperature, the activation and decomposition of residual components can be ensured at this temperature, while avoiding the impact of high temperatures on the stability of the electrolyte or other battery structures. Simultaneously, sufficient time ensures that the above process is fully realized.

[0024] In some embodiments, the formation temperature in the battery formation method is 42°C to 48°C.

[0025] Based on the above embodiments of this application, by limiting the ambient temperature during formation, the electrochemical reaction rate inside the battery can be increased, the film formation process can be accelerated, and high temperature can be avoided from damaging the battery.

[0026] In some embodiments, the ambient vacuum level in the battery formation method is -75kPa to 65kPa.

[0027] Based on the above embodiments of this application, by limiting the ambient vacuum during formation, the negative pressure environment can quickly expel the gas generated during the battery film formation process, thereby further improving the film formation effect.

[0028] According to a second aspect of this application, a battery manufacturing process is provided, which includes the battery formation method described above.

[0029] Based on the embodiments described above, the battery fabrication process provided by this application includes the aforementioned battery formation method. By dividing the charging process into three steps during battery formation and limiting the cutoff voltage in each of the three steps, the film formation rate of the solid electrolyte interface film during formation is improved. Furthermore, a resting time is set after each charge, with a longer resting time set for charging processes with higher film formation rates to repair the solid electrolyte interface film damaged by the expansion of the negative electrode active material. Finally, the above settings improve the film formation quality of the solid electrolyte interface film, thereby improving various performance characteristics of the battery, such as cycle life.

[0030] According to a third aspect of this application, a battery is provided, which is prepared using the battery manufacturing process described above.

[0031] Based on the above embodiments of this application, the battery disclosed in this application is prepared using the above-described battery preparation process, and therefore also has the above-described beneficial effects. To avoid repetition, it will not be described again here.

[0032] Other features and advantages of this application will be described in detail in the following detailed description section. Attached Figure Description

[0033] The accompanying drawings are provided to further illustrate the present application and form part of the specification. They are used together with the following detailed description to explain the present application, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic flowchart of the battery formation method provided in this application.

[0034] Figure 2 It is the differential capacity curve of a fully charged battery.

[0035] Figure 3 It is the differential capacity curve of the battery based on the negative electrode equilibrium potential during charging. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0037] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0038] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0039] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0040] In the description of this application, it should be noted that, unless otherwise stated, the terms "inner," "outer," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0041] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "setup" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0042] In the industrial production of lithium batteries, lithium iron phosphate is typically synthesized first using a liquid-phase method, followed by the preparation of the cathode slurry. During this process, fluctuations in the liquid-phase method can lead to intrinsic differences in the carbon coating thickness and microstructure of different batches of lithium iron phosphate raw materials. This, in turn, results in differences in the viscosity of the prepared cathode slurry. The viscosity difference of the cathode slurry directly affects the coating quality of the cathode sheet and the consistency of the subsequently manufactured batteries.

[0043] In the process of new energy battery manufacturing, formation is a crucial step. By charging with a small current, the electrolyte components form a solid electrolyte interphase (SEI) film on the surface of the battery active material. The quality of the SEI film formation directly affects the final performance of the battery.

[0044] Therefore, there is an urgent need to provide a battery formation method that improves the formation quality of the SEI film, thereby enhancing the battery's cycle life and other performance characteristics.

[0045] To address the aforementioned problems in the prior art, embodiments of this application provide a battery formation method, referencing... Figure 1 As shown, the battery formation method includes the following steps in sequence: S001 is initially charged with current I1 to the cutoff voltage V1, followed by a resting time t1.

[0046] S002 is charged for the second time with current I2 to charge the battery to the cutoff voltage V2, followed by a resting time t2.

[0047] S003 is charged for the third time with a current I3 to charge the battery to the cutoff voltage V3, followed by a resting time t3.

[0048] Among them, the cutoff voltage V1 is configured to be 2.7V~2.9V, the cutoff voltage V2 is configured to be 3.1V~3.3V, the cutoff voltage V3 is configured to be 3.2V~3.4V, and the settling time t1, settling time t2, and settling time t3 satisfy t1>t3 and t2>t3.

[0049] Based on the embodiments described above, during battery formation, the negative electrode active material expands during charging, causing damage to the solid electrolyte interface film formed on the surface of the negative electrode active material. Correspondingly, the faster the solid electrolyte interface film forms during charging, the more pronounced the expansion of the negative electrode active material becomes, leading to more severe damage to the solid electrolyte interface film already formed on the surface of the negative electrode active material.

[0050] In this application, the battery formation process is divided into three charging cycles and a resting cycle, and the cutoff voltage and resting time for each of the three charging cycles are defined. Specifically, refer to... Figure 2 and Figure 3 As shown in the figure. Among them, Figure 2 The horizontal axis represents the battery's charging voltage, and the vertical axis represents the battery's differential capacity. The four curves from top to bottom represent, in order, the experimental measurement results, the model fitting results, the model contribution of ethylene carbonate reduction to form a solid electrolyte interface, and the model contribution of ethylene carbonate reduction to form a solid electrolyte interface. Figure 3 The horizontal axis represents the negative electrode potential against lithium, and the vertical axis represents the differential capacity of the battery. From top to bottom, the three curves represent the model fitting results, the model contribution of ethylene carbonate reduction to form a solid electrolyte interface, and the model contribution of vinylene carbonate reduction to form a solid electrolyte interface, respectively.

[0051] Depend on Figure 2 and Figure 3 It can be seen that the curves show peaks at battery voltages of approximately 2.8V and 3.2V, and the voltage increase slows down, indicating that the film formation rate is relatively fast at these two potentials. Similarly, the film formation rate is also relatively fast at 3.3V. Based on this, the cutoff voltages for the three charging processes are set to approximately 2.8V, 3.2V, and 3.3V, respectively, so that a large-area solid electrolyte interface film can be formed on the surface of the negative electrode active material at a high film formation rate during the three charging processes.

[0052] Meanwhile, a resting time is set after each charge-to-film formation. During this time, metal ions in the negative electrode active material undergo deintercalation and reaction with the electrolyte to form a film, thereby repairing the solid electrolyte interface film damaged by the expansion of the negative electrode active material. During the first and second charges, the solid electrolyte interface film formation rate is high, resulting in significant expansion of the negative electrode active material and more noticeable damage to the formed solid electrolyte interface film. Therefore, a longer resting time is set in these cases to allow sufficient time for the battery to repair the solid electrolyte interface film. During the third charge, the film formation rate is lower than in the first and second charges, and the expansion of the negative electrode active material is relatively less. A shorter resting time can be set in this case, thus achieving both solid electrolyte interface film repair and formation efficiency.

[0053] In summary, this application divides the charging process during battery formation into three steps, and limits the cutoff voltage for each of the three steps, thereby improving the film formation rate of the solid electrolyte interfacial film during formation. Furthermore, a resting time is set after each charge, with a longer resting time for charging processes with higher film formation rates, to repair the solid electrolyte interfacial film damaged by the expansion of the negative electrode active material. Finally, these settings improve the film quality of the solid electrolyte interfacial film, thereby enhancing the battery's cycle life and other performance characteristics.

[0054] Furthermore, it should be noted that during the formation charging of a battery, taking a lithium battery as an example, a portion of the current is used for lithium intercalation, allowing lithium ions to embed into the negative electrode active material, while the other portion of the current is used for film formation. Therefore, by detecting the battery voltage, the degree of lithium intercalation in the negative electrode active material can be determined, and thus the film formation status of the battery can be indirectly judged.

[0055] In practical applications, this application obtained the formation and charging curves of lithium batteries through experimental testing. The curves show that the voltage increase slows down at approximately 2.8V and 3.2V, indicating that more current is used for the formation of the solid electrolyte interfacial film. This suggests a higher film formation rate at these points, but also more severe expansion of the negative electrode active material. Therefore, a resting period is necessary at this stage to repair the damage to the solid electrolyte interfacial film caused by the expansion of the negative electrode active material. Similarly, the formation and charging curves of the lithium battery show a significant change at 3.3V. Based on these factors, the cutoff voltages for the three charges during the lithium battery formation process are determined to be approximately 2.8V, 3.2V, and 3.3V, respectively.

[0056] Furthermore, it is understood that the above cutoff voltage is obtained by measuring the formation-charge curve of the lithium battery, and therefore this cutoff voltage cannot be directly applied to the formation process of other batteries. However, the battery formation method disclosed in this application, which determines the cutoff voltage based on the battery's formation-charge curve and sets the corresponding resting time to repair the solid electrolyte interface film according to the film formation rate at different cutoff voltages, can be adaptively adjusted to be applied to different batteries. Specifically, it can be set according to the battery type, and this application does not impose specific limitations in this regard.

[0057] In this application, the battery charging and formation process is divided into three specific charging steps, and the cutoff voltage and corresponding resting time for each step are limited to improve the film formation effect of the solid electrolyte interface film. The specific charging current rate and resting time for each step can be set according to the actual situation.

[0058] In some embodiments of this application, the current I1 can be configured to be 0.08C~0.15C, and the settling time t1 can be configured to be 10min~30min.

[0059] Based on the embodiments described above, specific limits are made to the initial charging current rate and the resting time. By setting a lower charging current rate, the proportion of inorganic matter in the formed solid electrolyte interface film increases, thereby improving the ionic conductivity and other properties of the solid electrolyte interface film, and enhancing the film formation quality. The specific limitation on the resting time ensures sufficient time for the battery to repair the damaged solid electrolyte interface film while also maintaining formation efficiency.

[0060] Specifically, in practical applications, the initial charging current rate can be set to multiple specific rates such as 0.08C, 0.10C, 0.12C, 0.14C, and 0.15C. Preferably, in some embodiments of this application, the initial charging current rate can be set to 0.10C. In practical applications, the resting time after the initial charging can be set to multiple specific times such as 10min, 15min, 20min, 25min, and 30min. Preferably, in some embodiments of this application, the resting time after the initial charging can be set to 10min.

[0061] Similarly, in some embodiments of this application, the current I2 can be configured to 0.1C~0.2C, and the settling time t2 can be configured to 10min~45min.

[0062] Based on the embodiments described above, similar to the initial charge, the current rate and resting time for the second charge are specifically defined. At this time, the charging current rate is increased compared to the initial charge, while still remaining at a relatively low current rate, thus ensuring both charging efficiency and film formation quality. The resting time is similar to that of the initial charge, taking into account both the repair of the solid electrolyte interface film and formation efficiency.

[0063] Specifically, in practical applications, the current rate of the second charge can be set to multiple specific rates such as 0.10C, 0.12C, 0.14C, 0.16C, 0.18C, and 0.20C. Preferably, in some embodiments of this application, the current rate of the second charge can be set to 0.15C. In practical applications, the resting time after the second charge can be set to multiple specific times such as 10min, 15min, 20min, 25min, 30min, 35min, 40min, and 45min. Preferably, in some embodiments of this application, the resting time after the second charge can be set to 30min.

[0064] Similarly, in some embodiments of this application, the current I3 is configured to be 0.15C~0.3C, and the settling time t3 is configured to be 1min~5min.

[0065] Based on the embodiments described above, the current rate and resting time during the third charge are also limited. At this time, the charging current rate is further increased compared to the first and second charges, allowing for a faster completion of the final charging process at a higher charging rate, thus improving formation efficiency. Simultaneously, the solid electrolyte interface film shows less damage during the third charge, therefore a shorter resting time is set to further improve formation efficiency.

[0066] Specifically, in practical applications, the current rate of the third charge can be set to multiple specific rates such as 0.15C, 0.17C, 0.20C, 0.23C, 0.25C, 0.27C, and 0.30C. Preferably, in some embodiments of this application, the current rate of the third charge can be set to 0.20C. The resting time after the third charge in practical applications can be set to multiple specific times such as 1 min, 2 min, 3 min, 4 min, and 5 min. Preferably, in some embodiments of this application, the resting time after the third charge can be set to 1 min.

[0067] Furthermore, it should be noted that while this application improves the specific charging steps in the battery formation process, other parts can be set with reference to existing technologies. For example, in some embodiments of this application, an open-circuit voltage test can be performed on the battery after three charging cycles.

[0068] Furthermore, in some embodiments of this application, reference is made to... Figure 1 As shown, the battery formation method also includes: S004 high-temperature aging, which involves heating the fully charged battery to temperature T and storing it for time t4 after the open-circuit voltage test to optimize the film formation effect.

[0069] Based on the above embodiments of this application, after charging and formation, the fully charged battery is heated at high temperature to activate and decompose some residual components in the solid electrolyte interface film, thereby further improving the film formation effect of the solid electrolyte interface film.

[0070] Specifically, in some embodiments of this application, the temperature T is configured to be 45°C and the time t4 is configured to be 12h-48h.

[0071] Based on the embodiments described above, by specifically limiting the heating temperature, the activation and decomposition of residual components can be ensured at this temperature, while avoiding the impact of high temperatures on the stability of the electrolyte or other battery structures. Simultaneously, sufficient time ensures that the above process is fully realized.

[0072] In practical applications, the high-temperature aging time can be set to multiple specific times such as 12h, 20h, 30h, 40h, and 48h. The specific time can be set according to factors such as actual process requirements. This application does not impose any specific restrictions on this.

[0073] In some embodiments of this application, the formation temperature in the battery formation method can be set to 42°C~48°C.

[0074] Based on the above embodiments of this application, by limiting the ambient temperature during formation, the electrochemical reaction rate inside the battery can be increased, the film formation process can be accelerated, and high temperature can be avoided from damaging the battery.

[0075] Specifically, in practical applications, the formation temperature during battery formation can be set to multiple specific values ​​such as 42°C, 44°C, 45°C, 46°C, and 48°C. Preferably, in some embodiments of this application, the formation temperature can be set to 45°C. The specific temperature can be set according to actual process requirements and other factors, and this application does not impose specific limitations on it.

[0076] Similarly, in some embodiments of this application, the ambient vacuum level in the battery formation method can be set to -75kPa to 65kPa.

[0077] Based on the above embodiments of this application, by limiting the ambient vacuum during formation, the negative pressure environment can quickly expel the gas generated during the battery film formation process, thereby further improving the film formation effect.

[0078] Based on the above technical solution, according to the second aspect of this application, a battery manufacturing process is provided, which includes the above-described battery formation method.

[0079] Based on the embodiments described above, the battery fabrication process provided by this application includes the aforementioned battery formation method. By dividing the charging process into three steps during battery formation and limiting the cutoff voltage in each of the three steps, the film formation rate of the solid electrolyte interface film during formation is improved. Furthermore, a resting time is set after each charge, with a longer resting time set for charging processes with higher film formation rates to repair the solid electrolyte interface film damaged by the expansion of the negative electrode active material. Finally, the above settings improve the film formation quality of the solid electrolyte interface film, thereby improving various performance characteristics of the battery, such as cycle life.

[0080] Furthermore, it should be noted that the battery manufacturing process disclosed in this application improves the solid electrolyte interface film quality by modifying the battery formation method. However, other steps in the battery manufacturing process, such as slurry preparation, coating, winding, and roll cutting, can be set with reference to existing technologies, and this application does not impose specific limitations on them.

[0081] Based on the above technical solutions, according to the third aspect of this application, a battery is provided, which is prepared using the above-described battery preparation process.

[0082] Based on the above embodiments of this application, the battery disclosed in this application is prepared using the above-described battery preparation process, and therefore also has the above-described beneficial effects. To avoid repetition, it will not be described again here.

[0083] The performance of the batteries prepared by the battery formation method and battery manufacturing process in this application will be further compared and illustrated below through two specific embodiments and a comparative example.

[0084] Example 1 This embodiment uses the battery formation method disclosed in this application to form a 280Ah lithium iron phosphate prismatic battery, as detailed below: First, the formation temperature was set to 45℃, and the ambient vacuum was set to -75kPa. Formation then began. During the initial charge, the battery was charged to 2.8V at a current rate of 0.10C, followed by a resting period of 10 minutes. During the second charge, the battery was charged to 3.2V at a current rate of 0.15C, followed by a resting period of 30 minutes. During the third charge, the battery was charged to 3.3V at a current rate of 0.20C, followed by a resting period of 1 minute.

[0085] An open-circuit voltage test was then performed. After the test, the battery was fully charged and stored in a 45-degree Celsius environment for 48 hours.

[0086] Example 2 This embodiment also uses the battery formation method disclosed in this application to form a 280Ah lithium iron phosphate prismatic battery. The formation method is basically the same as that in Example 1, except that: in Example 2, the current rate of the three charges is 0.15C, 0.20C and 0.30C respectively; the resting time after the three charges in Example 2 is 10min, 10min and 1min respectively; and no high-temperature aging is performed after the open circuit voltage test in Example 2.

[0087] Comparative Example The comparative example also involved the formation of a 280Ah lithium iron phosphate prismatic battery, as detailed below: First, the formation temperature was set to 45℃, and the ambient vacuum was set to -75kPa. Formation then began. During the initial charge, the battery was charged to 2.8V at a current rate of 0.10C, followed by a 1-minute rest. During the second charge, the battery was charged to 3.2V at a current rate of 0.15C, followed by a 1-minute rest. During the third charge, the battery was charged to 3.3V at a current rate of 0.20C, followed by a 1-minute rest.

[0088] Subsequently, cycle life tests were conducted on the batteries of Example 1, Example 2, and the comparative example after formation treatment, and the results are as follows: In Example 1, the battery retained 90.9% of its capacity after 2000 charge-discharge cycles.

[0089] In Example 2, the battery retained 89.7% of its capacity after 2000 charge-discharge cycles.

[0090] In the comparative example, the battery retained 86.1% of its capacity after 2000 charge-discharge cycles.

[0091] A comparison of Examples 1 and 2 with the comparative example shows that the battery formation method disclosed in this application can significantly improve the battery's cycle life. Furthermore, a comparison of Examples 1 and 2 shows that extending the post-charging resting time and subsequent high-temperature aging effectively improves the battery's cycle life. While Example 2's improvement in battery cycle life is less than that of Example 1, it still represents a significant improvement compared to the comparative example. Moreover, Example 2 shortens the formation time compared to Example 1, thereby improving production efficiency and reducing costs. Specific processing procedures can be set according to actual needs, referring to Examples 1 and 2; this application does not impose specific limitations in this regard.

[0092] The preferred embodiments of this application have been described in detail above with reference to the accompanying drawings. However, this application is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this application, various simple modifications can be made to the technical solution of this application, and these simple modifications all fall within the protection scope of this application.

[0093] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this application will not describe the various possible combinations separately.

[0094] Furthermore, various different implementations of this application can be combined in any way, as long as they do not violate the spirit of this application, they should also be regarded as the content disclosed in this application.

Claims

1. A battery formation method, characterized in that, The battery formation method includes the following steps in sequence: For the first charge, the battery is charged with current I1 to the cutoff voltage V1, followed by a resting time t1. The second charge involves charging the battery with current I2 to the cutoff voltage V2, followed by a resting time t2. The third charge involves charging the battery with a current of I3 to the cutoff voltage V3, followed by a resting time of t3. Wherein, the cutoff voltage V1 is configured to be 2.7V~2.9V, the cutoff voltage V2 is configured to be 3.1V~3.3V, the cutoff voltage V3 is configured to be 3.2V~3.4V, and the settling time t1, settling time t2, and settling time t3 satisfy t1>t3 and t2>t3.

2. The battery formation method according to claim 1, characterized in that, The current I1 is configured to be 0.08C~0.15C, and the settling time t1 is configured to be 10min~30min.

3. The battery formation method according to claim 1, characterized in that, The current I2 is configured to be 0.1C~0.2C, and the settling time t2 is configured to be 10min~45min.

4. The battery formation method according to claim 1, characterized in that, The current I3 is configured to be 0.15C~0.3C, and the settling time t3 is configured to be 1min~5min.

5. The battery formation method according to claim 1, characterized in that, The battery formation method further includes: high-temperature aging, which involves heating the fully charged battery to a temperature T and storing it for a time t4 to optimize the film formation effect.

6. The battery formation method according to claim 5, characterized in that, The temperature T is set to 45℃, and the time t4 is set to 12h-48h.

7. The battery formation method according to any one of claims 1-6, characterized in that, The formation temperature in the battery formation method is 42℃~48℃.

8. The battery formation method according to any one of claims 1-6, characterized in that, The environmental vacuum level in the battery formation method is -75kPa to 65kPa.

9. A battery manufacturing process, characterized in that, The battery manufacturing process includes the battery formation method as described in any one of claims 1-8.

10. A battery, characterized in that, The battery is prepared using the battery manufacturing process described in claim 9.

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